Protesters have targeted Tesco stores across the country to urge the supermarket giant to stop selling "deeply harmful" lads' mags.

The Lose the Lads' Mags campaign, led by pressure groups UK Feminista and Object, staged demonstrations in opposition to the retail chain's decision to continue selling magazines such as Nuts and Zoo to over 18s.

Displaying naked and near-naked images on magazine covers fuels attitudes underpinning violence against women and leave retailers facing the risk of legal action, the campaign group said. Exposing staff and customers to such images could constitute sex discrimination or sexual harassment, it claimed.

Speaking at the event, protest organiser Kat Banyard said Britain's largest supermarket chain must "show leadership" by no longer selling magazines which treat women as "sex objects". UK Feminista and Object have branded Tesco's decision earlier this month to restrict their sale of lads' mags to over 18s as an "inadequate half-measure".

It comes amid increasing debate about the effects of sexual images on children, with David Cameron recently setting out a raft of reforms which will introduce family-friendly filters that automatically block internet porn unless customers choose to opt out.

The Co-operative has confirmed it will no longer sell Nuts magazine from early next month after the title rejected an ultimatum to use ''modesty bags'' or be removed from shelves.

Domestic violence charity Women's Aid and the End Violence Against Women coalition have backed the Lose the Lads' Mags campaign, while 18 lawyers specialising in equality and discrimination law have signed an open letter calling on retailers to stop selling them.

Around 20 demonstrations took place outside Tesco stores across the UK including London, Northampton, Sheffield, Birmingham, Nottingham, Bristol, Glasgow and York.

A Tesco spokesman said the company had listened to customers on the issue of selling lads' mags in its stores and introduced new measures including restricting sales to over 18s and ensuring the magazines are displayed on the back tier of shelves. The supermarket chain also had assurances from publishers of Zoo, Nuts and Front that their covers would feature "more modest" images of women, he said.